Numerical Studies on Resonators Suitable for DLR-COIL

Abstract

Off-axis negative-branch and off-axis positive-branch hybrid resonators, suitable for a laser with large medium cross section and a small output coupling are explored numerically. With r espect to mirror tilting, the calculations confirm that in unstable direction the off-axis negative-branch resonator is less sensitive to mirror misalignments than the off-axis positive-branch one. In stable direction, the sensitivity to mirror misalignment is larger than in unstable direction and dependent on mirror curvature. The fabrication of cylindrical mirrors for such hybrid resonators is difficult and deviations in mirror radius of curvature are possible. The effects of such deviations are addressed. Near the ideal mirror parameters, the off-axis negative-branch unstable resonator is insensitive to mirror curvature variations if the resonator length is appropriately adapted to the mirror curvatures.